ABSTRAK

Kesuburan suatu perairan tergantung pada kandungan zat hara di perairan antara lain nitrat dan fosfat. Senyawa fosfat dan nitrat merupakan zat hara yang dijadikan petunjuk kesuburan perairan dan dibutuhkan fitoplankton dalam pertumbuhan dan perkembangan hidupnya. Tujuan penelitian adalah mengetahui kadar senyawa nitrat, fosfat dan kelimpahan fitoplankton yang ada di Sub DAS Riam Kanan, mengetahui kesuburan perairan Sub DAS Riam Kanan berdasarkan nitrat, fosfat dan kelimpahan fitoplankton, mengetahui hubungan nitrat, fosfat, dan kelimpahan fitoplankton dengan variabel kualitas air seperti suhu, DO dan pH. Hasil penelitian menyimpulkan bahwa Kadar senyawa nitrat berdasarkan penelitian di Sub DAS Riam Kanan pada bulan Agustus dan September secara berurutan adalah ST I 0,3 mg/l dan 1,0 mg/l, ST II 0,6 mg/l dan 0,9 mg/l, ST III 0,7 mg/l dan 0,9 mg/l. Kadar fosfat pada bulan Agustus dan September secara berurutan adalah ST I 0,16 mg/l dan 0,14 mg/l, ST II 0,25 mg/l dan 0,13 mg/l, ST III 0,15 mg/l dan 0,17 mg/l. Kadar kelimpahan fitoplankton pada bulan Agustus dan September adalah ST I 10.890 sel/l dan 13.060 sel/l, ST II 4.610 sel/l dan 10.000 sel/l, ST III 8.060 sel/l dan 11.080 sel/l. Kesuburan perairan Sub DAS Riam Kanan berdasarkan kadar nitrat, fosfat dan kelimpahan fitoplankton tergolong dalam tingkat kesuburan mesotrofik. Hasil analisis uji regresi linier sederhana memperlihatkan bahwa keeratan hubungan (korelasi) berdasarkan nilai R yang tergolong korelasi dari kuat sampai sangat kuat adalah hubungan fosfat dan suhu, fosfat dan oksigen terlarut, serta fosfat dan derajat keasaman dengan nilai korelasi yaitu 0,854-0,999. Korelasi berdasarkan nilai R yang tergolong sangat lemah adalah hubungan kelimpahan fitoplankton dan derajat keasaman dengan nilai korelasi adalah 0,014.

Kata Kunci: kesuburan perairan, nitrat, fosfat, kelimpahan fitoplankton, riam kanan

ABSTRACT

Eutrophication is something in water depending on the nutrients in the waters including nitrates and phosphates. Phosphate and nitrate compounds are nutrients that are used as indicators of water eutrophication and are needed by phytoplankton for their growth and development. The aim of the study was to determine the levels of nitrate, phosphate and phytoplankton abundance in the Riam Kanan Sub-watershed, to determine the eutrophication of the waters of the Riam Kanan Sub-watershed based on nitrate, phosphate and phytoplankton abundance, to determine the relationship between nitrate, phosphate and phytoplankton abundance with water quality variables such as temperature, DO and pH. The results of the study concluded that the levels of nitrate compounds based on research in the Riam Kanan Sub-watershed in August and September respectively were ST I 0.3 mg/l and 1.0 mg/l, ST II 0.6 mg/l and 0.9 mg/l, ST III 0.7 mg/l and 0.9 mg/l. Phosphate levels in August and September respectively were ST I 0.16 mg/l and 0.14 mg/l, ST II 0.25 mg/l and 0.13 mg/l, ST III 0.15 mg/l and 0.17 mg/l. Phytoplankton abundance levels in August and September were ST I 10,890 cells/l and 13,060 cells/l, ST II 4,610 cells/l and 10,000 cells/l, ST III 8,060 cells/l and 11,080 cells/l. The eutrophication of the waters of the Riam Kanan Sub-watershed based on levels of nitrate, phosphate and abundance of phytoplankton is classified as mesotrophic. The results of a simple linear regression test analysis show that the correlation based on the R value, which is classified as a correlation from strong to very strong, is the relationship between phosphate and temperature, phosphate and dissolved oxygen, as well as phosphate and acidity with a correlation value of 0.854-0.999. The correlation based on the R value which is classified as very weak is the relationship between the abundance of phytoplankton and the degree of acidity with a correlation value of 0.014.

Keywords: water eutrophication, nitrate, phosphate, abundance of phytoplankton, riam kanan